Integral negative/positive color diffusion transfer process film unit employing in-situ generated visible light-reflecting agent

ABSTRACT

This application is directed, in general, to an integral negative/positive color diffusion transfer process film unit which includes, in order, an opaque layer, a photosensitive silver halide layer having associated dye transfer image-forming material, a layer comprising a light-reflecting agent precursor which comprises, upon contact with a processing composition, first ionic species adapted to interact with second ionic species to provide a substantially white, inorganic visible lightreflecting agent, a polymeric layer adapted to be dyed by the dye transfer image-forming material, a transparent layer, and means for distributing a processing composition between the dyeable polymeric layer and the photosensitive silver halide layer, and to specified diffusible transfer color processes employing such a film unit.

United States Patent Land [ Mar. 7, 1972 [54] INTEGRAL NEGATIVE/POSITIVECOLOR DIFFUSION TRANSFER PROCESS FILM UNIT EMPLOYING IN- SITU GENERATEDVISIBLE LIGHT- REFLECTING AGENT [72] Inventor: Edwin H. Land, Cambridge,Mass.

{73] Assignee: Polaroid Corporation, Cambridge, Mass.

[22] Filed: June 5, 1970 [2]] Appl. No.: 43,742

[52] US. Cl ..96/3, 96/29 D, 96/84 R, 96/76 C [5 1] Int. Cl ..G03c 7/00,G03c 5/54, G03c H84 [58] Field of Search ..96/3, 29 D, 84 R [56]References Cited UNITED STATES PATENTS 3,415,644 12/1968 Land ..96/3

Primary Examiner-Norman G. Torchin Assistant Examiner-Alfonso T. SuroPico Att0meyBrown and Mikulka and Robert M. Ford [57] ABSTRACT Thisapplication is directed, in general, to an integral negative/positivecolor diffusion transfer process film unit which includes, in order, anopaque layer, a photosensitive silver halide layer having associated dyetransfer image-forming material, a layer comprising a light-reflectingagent precursor which comprises, upon contact with a processingcomposition, first ionic species adapted to interact with second ionicspecies to provide a substantially white, inorganic visiblelight-reflecting agent, a polymeric layer adapted to be dyed by the dyetransfer image-forming material, a transparent layer, and means fordistributing a processing composition between the dyeable polymericlayer and the photosensitive silver halide layer, and to specifieddiffusible transfer color processes employing such a film unit.

42 Claims, 7 Drawing Figures LAYER I DYE DEVELOPER LAYER SENSITIVESILVER HALIDE EMULSION LAYER DYE DEVELOPER LAYER SILVER HALIDE EMULSIONLAYER DEVELOPER LAYER SILVER HALIDE EMULSION LAYER COM POSITIONCONTAINING AGENT LAYER LAYER PATENTE'DMAR 7 m2 SHFET 3 [IF 4 INVENTOR.EDWIN H. LAND BY fihouprb and MIA W (MM; 1?? (WM .ATTORNF'YS INTEGRALNEGATIVE/POSITIVE COLOR DIFFUSION TRANSFER PROCESS FILM UNIT EMPLOYINGIN-SITU GENERATED VISIBLE LIGHT-REFLECTING AGENT The present inventionrelates to photography and, more particularly, to photographic productsspecifically adapted for employment in photographic diffusion transfercolor processes.

The primary objects of the invention are to provide photographicproducts particularly adapted for employment in diffusion transfer colorprocesses; to provide photographic products which comprise aphotosensitive composite structure which contains a plurality ofessential layers including a dimensionally stable opaque layer, aphotosensitive silver halide emulsion layer having a dye image-formingmaterial associated therewith which is soluble and diffusible inprocessing composition as a function of exposure of the photosensitivesilver halide emulsion layer to incident actinic radiation, a layerpermeable to processing composition diffusible dye image-formingmaterial comprising a reflecting agent precursor in a quantitysufficient to mask dye image-forming material associated with thephotosensitive silver halide emulsion layer subsequent to and as afunction of processing, a polymeric layer dyeable by the dyeimage-forming material, and a dimensionally stable transparent layer; toprovide photographic diffusion transfer products comprising a film unitincluding a photosensitive laminate, of the last-identified type, incombination with a rupturable container retaining a processingcomposition and preferably containing dispersed therein an opacifyingagent in a quantity effective to prevent exposure of the photosensitivesilver halide emulsion layer in the presence of actinic radiationincident on the dimensionally stable transparent layer, the reflectingagent preferably generated in a quantity sufficient to mask both theopacifying agent and dye image-forming material associated with thephotosensitive silver halide emulsion layer subsequent to diffusiontransfer processing; to provide a diffusion transfer film unit, of thelast-identified type, having the container fixedly positioned andextending transverse a leading edge of the photosensitive compositestructure whereby to effect, upon application, of compressive pressure,discharge of the processing composition intermediate opposed surfaces ofthe dyeable polymeric layer and the photosensitive silver halideemulsion and associated dye image-forming material next adjacentthereto, and, in the preferred embodiment, intermediate the opposedsurfaces of the processing composition permeable reflecting agentprecursor containing layer and the photosensitive silver halide emulsionlayer and associated dye image-forming material next adjacent thereto;and to provide photographic diffusion transfer color processes employingsuch products.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the product possessing the features,properties and the relation of components and the process involving theseveral steps and the relation and order of one or more of such stepswith respect to each of the others which are exemplified in thefollowing detailed disclosure, and the scope of the application of whichwill be indicated in the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawings wherein:

FIG. 1 is a perspective view of a photographic film unit embodying theinvention;

FIGS. 2, 4 and 6 are diagrammatic enlarged cross-sectional views of thefilm unit of FIG. 1, along section line 2-2, illustrating theassociation of elements during the three illustrated stages of theperformance of a diffusion transfer process, for the production of amulticolor transfer image according to the invention, the thickness ofthe various materials being exaggerated, and wherein FIG. 2 representsan exposure stage, FIG. 4 represents a processing stage and FIG. 6represents a product of the process; and

FIGS. 3, 5 and 7 are diagrammatic, further enlarged crosssectional viewsof the film unit of FIGS. 2, 4 and 6, along section lines 3-3, 5-5 and77, respectively, further illustrating, in detail, the arrangement oflayers comprising the photosensitive laminate during the threeillustrated stages of the transfer process.

As disclosed in U.S. Pat. No. 2,983,606, issued May 9, 1961, aphotosensitive element containing a dye developer, that is, a dye whichis a silver halide developing agent, and a silver halide emulsion may beexposed and wetted by a liquidprocessing composition, for example, byimmersion, coating, spraying, flowing, etc., in the dark, and theexposed photosensitive element superposed prior to, during, or afterwetting, on a sheetlike support element which may be utilized as animage-receiving element. In a preferred embodiment, theliquid-processing composition is applied to the photosensitive elementin a substantially uniform layer as the photosensitive element isbrought into superposed relationship with the image-receiving layer. Theliquid-processing composition, positioned intermediate thephotosensitive element and the image-receiving layer, permeates theemulsion to initiate development of the latent image contained therein.The dye developer is immobilized or precipitated in exposed areas as aconsequence of the development of the latent image. This immobilizationis apparently, at least in part, due to a change in the solubilitycharacteristics of the dye developer upon oxidation and especially asregards its solubility in alkaline solutions. It may also be due in partto a tanning effect on the emulsion by oxidized developing agent, and inpart to a localized exhaustion of alkali as a result of development. Inunexposed and partially exposed areas of the emulsion, the dye developeris unreacted and diffusible and thus provides an imagewise distributionof unoxidized dye developer dissolved in the liquid processingcomposition, as a function of the point-to-point degree of exposure ofthe silver halide emulsion. At least part of this imagewise distributionof unoxidized dye developer is transferred, by imbibition, to asuperposed image-receiving layer or element, said transfer substantiallyexcluding oxidized dye developer. The image-receiving element receives adepthwise diffusion, from the developed emulsion, of unoxidized dyedeveloper without appreciably disturbing the imagewise distributionthereof to provide the reversed or positive color image of the developedimage. The image-receiving element may contain agents adapted to mordantor otherwise fix the diffused, unoxidized dye developer. If the color ofthe transferred dye developer is affected by changes in the pH of theimage-receiving element, this pH may be adjusted in accordance withwell-known techniques to provide a pH affording the desired color. Thedesired positive image is revealed by stripping the image-receivinglayer from the photosensitive element at the end of a suitableimbibition period.

The dye developers, as noted above, are compounds which contain, in thesame molecule, both the chromophoric system of a dye and also a silverhalide developing function. By a silver halide developing function ismeant a grouping adapted to develop exposed silver halide. A preferredsilver halide development function is a hydroquinonyl group. Othersuitable developing functions include ortho-dihydroxyphenyl and orthoandpara-amino substituted hydroxyphenyl groups. In general, the developmentfunction includes a benzenoid developing function, that is, an aromaticdeveloping group which forms quinonoid or quinone substances whenoxidized.

Multicolor images may be obtained using color image-forming componentssuch as, for example, the previously mentioned dye developers, indiffusion transfer processes by several techniques. One such techniquecontemplates obtaining multicolor transfer images utilizing dyedevelopers by employment of an integral multilayer photosensitiveelement, such as is disclosed in the aforementioned U.S. Pat. No.2,983,606, and particularly with reference to FIG. 9 of the patentsdrawing, wherein at least two selectively sensitized photosensitivestrata, superposed on a single support, are processed, simultaneouslyand without separation, with a single, common image-receiving layer. Asuitable arrangement of this type comprises a support carrying ared-sensitive silver halide emulsion stratum, a green-sensitive silverhalide emulsion stratum and a blue-sensitive silver halide emulsionstratum, said emulsions having associated therewith, respectively, forexample, a cyan dye developer, a magenta dye developer and a yellow dyedeveloper. The dye developer may be utilized in the silver halideemulsion layer, for example, in the form of particles, or it may beemployed as a layer behind the appropriate silver halide emulsionstrata. Each set of silver halide emulsion and associated dye developerstrata are disclosed to be optionally separated from other setsbysuitable interlayers, for example, by a layer of gelatin or polyvinylalcohol. In certain instances, it may be desirable to incorporate ayellow filter in front of the green-sensitive emulsion and such yellowfilter may be incorporated in an interlayer. However, where desirable, ayellow dye developer of the appropriate spectral characteristics andpresent in a state capable of functioning as a yellow filter may beemployed. In such instances, a separate yellow filter may be omitted.

The dye developers are preferably selected for their ability to providecolors that are useful in carrying out subtractive color photography,that is, the previously mentioned cyan, magenta and yellow. The dyedevelopers employed may be incorporated in the respective silver halideemulsion or, in the preferred embodiment, in a separate layer behind therespective silver halide emulsion.- Specifically, the dye developer may,for example, be in a coating or layer behind the respective silverhalide emulsion and such a layer of dye developer may be applied by useof a coating solution containing about 0.5 to 8 percent, by weight, ofthe respective dye developer distributed in a film-forming natural, orsynthetic, polymer, for example, gelatin, polyvinyl alcohol, and thelike, adapted to be permeated by the chosen diffusion transferfluidprocessing composition.

As examples of materials, for use as the image-receiving layer, mentionmay be made of solution dyeable polymers such as nylon as, for example,N-methoxymethyl polyhexamethylene adipamide; partially hydrolyzedpolyvinyl acetate; polyvinyl alcohol with or without plasticizers;cellulose acetate with filler as, for example, one-half celluloseacetate and one-half oleic acid; gelatin; and other materials of asimilar nature. Preferred materials comprise polyvinyl alcohol orgelatin containing a dye mordant such as poly-4-vinylpyridine, asdisclosed in US. Pat. No. 3,148,061, issued Sept. 8, 1964.

As disclosed in the previously cited patents, the liquidprocessingcomposition referred to for effecting multicolor diffusion transferprocesses comprises at least an aqueous solution of an alkalinematerial, for example, diethylamine, sodium hydroxide or sodiumcarbonate and the like, and preferably possessing a pH in excess of 12,and most preferably includes a viscosity-increasing compoundconstituting a film-forming material of the type which, when thecomposition is spread and dried, forms a relatively firm and relativelystable film. The preferred film-forming materials disclosed comprisehigh molecular weight polymers such as polymeric, water-soluble etherswhich are inert to an alkaline solution such as, for example, ahydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally,film-forming materials or thickening agents whose ability to increaseviscosity is substantially unaffected if left in solution for a longperiod of time are also disclosed to be capable of utilization. Asstated, the film-forming material is preferably contained in theprocessing composition in such suitable quantities as to impart to thecomposition a viscosity in excess of 100 cps. at a temperature ofapproximately 24 C. and preferably in the order of 100,000 cps. to200,000 cps. at that temperature.

in accordance with aforementioned US. Pat. No. 2,983,606, animage-receiving layer of the type disclosed in that patent need not beseparated from its superposed contact with the photosensitive element,subsequent to transfer image formation, if the image-receiving elementis transparent and a processing composition containing a substancerendering the processing composition layer opaque is spread between theimage-receiving layer and the silver halide emulsion or emulsrons.

However, it has been found, if the image-receiving element is maintainedin contact with the photosensitive element, subsequent to dye developertransfer image formation, and includes the presence of analkaline-processing composition, necessarily having a pH at which dyedeveloper, for example, in reduced form, diffuses to form the dyetransfer image, intermediate the elements, the transfer image thusformed is unstable over an extended period of time. The dye imageinstability is due, at least in part to the presence of what is, ingeneral, a relatively high pH alkaline composition in intimate contactwith the dye or dyes forming the image. This contact itself providesinstability to the molecular structure of dye by, for example,catalyzing degradation and undesirable structural shifts effecting thespectral absorption characteristics of the image dye. in addition, thepresence of an alkaline composition, possessing a pH at which the dye,for example, in reduced form, diffuses, also provides an integraldynamic system wherein oxidized dye, immobilized in areas of thephotosensitive element, as a function of its development, with thepassage of time attempts to generate, in such areas, an equilibriumbetween oxidized and reduced dye. In that the pH of the dynamic systemis such that diffusion of the reduced form of the dye will occur, suchreduced dye will, at least in part, transfer to the image-receivinglayer and the resultant difi'usion will imbalance the equilibrium, insuch areas of the photosensitive element, in favor of additionalformation of reduced dye. As a function of the efficiency of theimagereceiving layer, as a dye sink, such nonimagewise dyeing of theimage-carrying layer will still further imbalances the equilibrium infavor of the additional formation of dye in reduced, diffusible form.Under such circumstances, the transfer image definition, originallycarried by the image-receiving layer, will suffer a continuous decreasein the delta between the images maximum and minimum densities and may,ultimately, result in the image-receiving elements loss of all semblanceof image definition; merely becoming a polymeric stratum carrying arelatively uniform overall dyeing.

Any attempt to decrease the dye sink capacity of the imagecarryinglayer, for example, by reduction of its mordant capacity, in order toalleviate, at least to an extent, the action of the image-receivinglayer as a dye sink, however, will enhance diffusion of the dye,comprising the transfer image, from the image-carrying layer, to theremainder of the element due, at least in part, to the continuedpresence of the alkaline composition having a pH at which the reducedform of the dye, forming the transfer image, is diffusible. The ultimateresult is substantially the same overall image distortion as occurs whenthe image-receiving layer acts as a dye sink, with the exception thatthe dye is more extensively distributed throughout the film unit and theultimate overall dyeing of the image-receiving layer itself is of lowersaturation.

The problems inherent in fabricating a film unit of the type wherein theimage-receiving element, the alkaline processing composition and thephotosensitive element are maintained in contiguous contact subsequentto dye transfer image formation, for example, a film unit of the typedescribed hereinbefore with reference to aforementioned US. Pat. No.2,983,606, may be effectively obviated by fabrication of a film unit inaccordance with the physical parameters specifically set forth in US.Pat. Nos. 3,4l5,644; 3,415,645; and 3,415,646, issued Dec. 10, 1969,respectively, in the name of Edwin H. Land.

Specifically an integral photographic film unit particularly adapted forthe production of a dye transfer image of unexpectedly improvedstability and other properties, by a color diffusion transfer processwill be constructed, for example, in accordance with aforementioned US.Pat. No. 3,415,644, to include a photosensitive element comprising alaminate having, in sequence, as essential layers, a dimensionallystable opaque layer;'a photosensitive silver halide emulsion layerhaving associated therewith dye image-providing material which issoluble and diffusible, in alkali, at a first pH; an alkaline solutionpermeable polymeric layer dyeable by the dye image-providing material; apolymeric acid layer containing sufficient acidifying groups to effectreduction, subsequent to substantial transfer dye image formation, of aselected processing solution having the first pH to a second pH at whichsaid dye image-providing material is insoluble and nondiffusible; and adimensionally stable transparent layer. In combination with thelaminate, a rupturable container retaining an aqueous alkalineprocessing composition having the first pH and containing an opacifyingagent, in a quantity sufficient to mask the dye image-providingmaterial, is fixedly positioned and extends transverse a leading edge ofthe laminate whereby to effect unidirectional discharge of thecontainers contents between the alkaline solution permeable and dyeablepolymeric layer and the photosensitive silver halide emulsion layer nextadjacent thereto, upon application of compressive force to thecontainer.

It will also be recognized that the dimensionally stable polymericsupport layer next adjacent the photosensitive silver halide emulsionlayer or layers may be transparent, as disclosed in aforementioned U.S.Pat. No. 3,415,646, and that in such instance the opacifying agent maybe initially dispersed in the composite film unit intermediate thedyeable polymeric layer and the silver halide emulsion layer nextadjacent, as disclosed in aforementioned U.S. Pat. No. 3,415,645.

Employment of the last-mentioned film units, according to the describedcolor diffusion transfer photographic process, specifically provides forthe production of a highly stable color transfer image accomplished, atleast in part, by effectively obviating the previously discusseddisadvantages of the prior art products and processes, by in processadjustment of the environmental pH of the film unit from a pH at whichtransfer processing is operative to a pH at which dye transfer isinoperative subsequent to substantial transfer image formation. Thestable color transfer image is obtained irrespective of the fact thatthe film unit is maintained as an integral laminate unit duringexposure, processing, viewing, and storage of the unit, which transferimage exhibits the required maximum and minimum dye transfer imagedensities, dye saturation, hues and definition.

Film units fabricated in accordance with the parameter set forth abovespecifically disclose the presence of the stated polymeric acidcomponent to effect in situ process adjustment of the film unitsoperational pH range.

Specifically, the film units require the presence of a polymeric acidlayer such as, for example, of the type set forth in U.S. Pat. No.3,362,819 which, most preferably, includes the presence of an inerttiming or spacer layer intermediate the polymeric acid layer carried ona support and the imagereceiving layer.

As set forth in the last-mentioned patent, the polymeric acid layercomprises polymers which contain acid groups, such as carboxylic acidand sulfonic acid groups, which are capable of forming salts with alkalimetals, such as sodium, potassium etc., or with organic bases,particularly quaternary ammonium bases, such as tetrarnethyl ammoniumhydroxide, or potentially acid-yielding groups, such as anhydrides orlactones, or other groups which are capable of reacting with bases tocapture and retain them. The acid-reacting group is, of course,nondiffusible from the acid polymer layer. In the preferred embodimentsdisclosed, the acid polymer contains free carboxyl groups and thetransfer processing composition employed contains a large concentrationof sodium and/or potassium ions. The acid polymers stated to be mostuseful are characterized by containing free carboxyl groups, beinginsoluble in water in the free acid form, and by forming watersolublesodium and/or potassium salts. One may also employ polymers containingcarboxylic acid anhydride groups, at least some of which preferably havebeen converted to free carboxyl groups prior to imbibition. While themost readily available polymeric acids are derivatives of cellulose orof vinyl polymers, polymeric acids from other classes of polymers may beused. As examples of specific polymeric acids set forth in theapplication, mention may be made of dibasic acid halfester derivativesof cellulosewhich derivatives contain free carboxyl groups, e.g.,cellulose acetate hydrogen phthalate, cellulose acetate hydrogenglutarate, cellulose acetate hydrogen succinate, ethyl cellulosehydrogen succinate, ethyl cellulose acetate hydrogen succinate,cellulose acetate hydrogen succinate hydrogen phthalate; ether and esterderivatives or cellulose modified with sulfoanhydrides, e.g., withortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethylcellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogenphthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxyor sulfo substituted aldehydes, e.g., o-, m-, or p-benzaldehyde sulfonicacid or carboxylic acid; partial esters of ethylene/maleic anhydridecopolymers; partial esters of methyl-vinyl ether/maleic anhydridecopolymers; etc.

As previously noted, the pH of the processing composition preferably isof the order of at least 12 to 14. The acid polymer layer is disclosedto contain at least sufficient acid groups to effect a reduction in thepH of the image layer from a pH of about 12 to 14 to a pH of at least Il or lower at the end of the imbibition period, and preferably to a pHof about 5 to 8 within a short time after imbibition, thus requiring, ofcourse, that the action of the polymeric acid be accurately socontrolled as not to interfere with either development of the negativeor image transfer of unoxidized dye developers. For this reason, the pHof the image layer must be kept at a functional transfer level, forexample, 12 to 14 until the dye image has been formed after which the pHis reduced very rapidly to a pH below that at which dye transfer may beaccomplished, for example, at least about 11 and preferably about pH 9to l0. Unoxidized dye developers containing hydroquinonyl developingradicals diffuse from the negative to the positive as the sodium orother alkali salt. The diffusion rate of such dye image-formingcomponents thus is at least partly a function of the alkaliconcentration, and it is necessary that the pH of the image layer remainon the order of, for example, 12 to 14 until transfer of the necessaryquantity of dye has been accomplished. The subsequent pH reduction, inaddition to its desirable effect upon image light stability, serves ahighly valuable photographic function by substantially terminatingfurther dye transfer.

in order to prevent premature pH reduction during transfer processing,as evidenced, for example, by an undesired reduction in positive imagedensity, the acid groups are disclosed to be so distributed in the acidpolymer layer that the rate of their availability to the alkali iscontrollable, e.g., as a function of the rate of swelling of the polymerlayer which rate in turn has a direct relationship to the diffusion rateof the alkali ions. The desired distribution of the acid groups in theacid polymer layer may be effected by mixing the acid polymer with apolymer free of acid groups, or lower in concentration of acid groups,and compatible therewith, or by using only the acid polymer butselecting one having a relatively lower proportion of acid groups. Theseembodiments are illustrated, respectively, in the cited copendingapplication, by (a) a mixture of cellulose acetate and cellulose acetatehydrogen phthalate and (b) a cellulose acetate hydrogen phthalatepolymer having a much lower percentage of phthalyl groups than thefirst-mentioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acidmay contain a water-insoluble polymer, preferably a cellulose ester,which acts to control or modulate the rate at which the alkali salt ofthe polymer acid is formed. As examples of cellulose esters contemplatedfor use, mention is made of cellulose acetate, cellulose acetatebutyrate, etc. The particular polymers and combinations of polymersemployed in any given embodiment are, of course, selected so as to haveadequate wet and dry strength and when necessary or desirable, suitablesubcoats are employed to help the various polymeric layers adhere toeach other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, aninert spacer layer comprising polyvinyl alcohol or gelatin, acts to timecontrol the pH reduction by the polymeric acid layer. This timing isdisclosed to be a function of the rate at which the alkali diffusesthrough the inert spacer layer. It is there stated to have been foundthat the pH does not drop until the alkali has passed through the spacerlayer, i.e., the pH is not reduced to any significant extent by the merediffusion into the interlayer, but the pH drops quite rapidly once thealkali diffuses through the spacer layer.

It has now been quite unexpectedly discovered that the problems inherentin fabricating a film unit of the type where the image-receivingelement, the alkali processing composition and the photosensitiveelement are maintained in contiguous contact during processing andsubsequent to dye transfer image formation, for example, a film unit ofthe type described, with reference to aforementioned U.S. Pat. No.2,983,606, may be effectively obviated in a considerably simplifiedmanner by fabrication of a film unit in accordance with the physicalparameters detailed below.

Specifically, it has been quite unexpectedly ;iscovered that an integralphotographic film unit of simplified construction and particularlyadapted for the production of dye transfer images of unexpectedlyimproved stability and other desirable properties by a color diffusiontransfer processwill be constructed to include a photosensitive elementcomprising a composite structure possessing, in sequence, as essentiallayers: a ;imensionally stable opaque layer; a photosensitive silverhalide emulsion layer having associated therewith a dye image-fonningmaterial which is soluble and diffusible in processing composition as afunction of the point-to-point degree of exposure of the photosensitivesilver halide emulsion layer to incident actinic radiation; a layerpermeable to processing composition diffusible dye image-formingmaterial which comprises a reflecting agent precursor present in aconcentration sufficient to mask dye image-forming material associatedwith the photosensitive silver halide emulsion layer subsequent to andas a function of processing; a polymeric layer dyeable by the dyeimage-forming material; and a dimensionally stable transparent layer. Incombination with the composite structure, a rupturable containerretaining a processing composition is fixedly positioned and extendstransverse a leading edge of the composite structure whereby to effect,upon application of compressive pressure, discharge of the processingcomposition intermediate the dyeable polymeric layer and thephotosensitive silver halide emulsion layer and associated dyeimage-forming material next adjacent. In the preferred embodiment of thepresent invention, an opacifying agent is initially disposed in theprocessing composition retained by the rupturable container and thecontainer is fixedly positioned and extends transverse the leading edgeof the composite structure whereby to effect, upon application ofcompressive pressure, discharge of the processing compositionintermediate opposed surfaces of the processing composition permeablereflecting agent precursor containing layer and the photosensitivesilver halide emulsion layer and associated dye image-forming materialnext adjacent and the opacifying agent is present in a concentrationwhich is effective, upon distribution, to prevent exposure of thephotosensitive silver halide emulsion layer in the presence of actinicradiation incident on the dimensionally stable transparent layer and tomask dye image-forming material associated with the silver halideemulsion layer and the reflecting agent generated is also present in aconcentration sufficient to mask distributed opacifying agent.

In a preferred embodiment of the present invention, the film unit isspecifically adapted to provide for the production of a multicolor dyetransfer image and the photosensitive laminate comprises, in order ofessential layers, the dimensionally stable opaque layer; at least twoselectively sensitized silver halide emulsion strata each having dyeimage-providing materials of predetermined color associated therewithwhich are soluble and diffusible in alkaline processing composition as afunction of the point-to-point degree of exposure of the respectiveassociated silver halide emulsion strata; a polymeric layer permeable byalkaline processing composition solubilized dye image-providingmaterials which contain a reflecting agent precursor in a quantitysufficient to mask the dye imageproviding materials associated with theselectively sensitized silver halide emulsion strata subsequent toprocessing; a polymeric layer dyeable by the dye image-providingmaterial; and the dimensionally stable transparent layer.

In view of the fact that the preferred dye image-providing materialscomprise dyes which are silver halide developing agents, as statedabove, for purposes of simplicity and clarity, the present inventionwill be further described hereinafter in terms of such dyes, withoutlimitation of the invention to the illustrative dyes denoted,and, inaddition the photographic film unit structure will be detailedhereinafter employing the last-mentioned preferred structuralembodiment, without limitation of the invention to the preferredstructure denoted.

The silver halide emulsions comprising the multicolor photosensitivelaminate preferably possess predominant spectral sensitivity to separateregions of the spectrum and each has associated therewith a dye, whichis a silver halide developing agent and is, most preferably,substantially soluble in the reduced form only at a first pH possessing,subsequent to processing, a spectral absorption range substantiallycomplementary to the predominant sensitivity range of its associatedemulsion.

In the preferred embodiment, each of the emulsion strata, and itsassociated dye, is separated from the remaining emulsion strata, andtheir associated dye, by separate alkaline solution permeable polymericinterlayers.

In such preferred embodiment of the invention, the silver halideemulsion comprises photosensitive silver halide dispersed in gelatin andis about 0.6 to 6 microns in thickness; the dye itself is dispersed inan aqueous alkaline solution polymeric binder, preferably gelatin, as aseparate layer about 1 to 7 microns in thickness; the alkaline solutionpermeable polymeric interlayers, preferably gelatin, are about I to 5microns in thickness; the reflecting agent precursor containing layer isabout 0.05 to 0.25 micron in thickness; the dyeable polymeric layer istransparent and about 0.25 to 0.4 mil. in thickness; and each of thedimensionally stable opaque and transparent layers are alkaline solutionimpermeable, processing composition vapor permeable and about 2 to 6mils. in thickness. It will be specifically recognized that the relativedimensions recited above may be appropriately modified, in accordancewith the desires of the operator, with respect to the specific productto be ultimately prepared.

In the preferred embodiment of the present invention 's film unit forthe production of a multicolor transfer image, the respective silverhalide/dye developer units of the photosensitive element will be in theform of a tripack configuration which will ordinarily comprise a cyandye developer/red-sensitive emulsion unit contiguous the dimensionallystable opaque layer, the yellow dye developer/blue-sensitive emulsionunit most distant from the opaque layer and the magenta dyedevelop'r'lgreen-sensitive emulsion unit intermediate those units,recognizing that the relative order of such units may be varied inaccordance with the desires of the operator.

Reference is now made to FIGS. 1 through 7 of the drawings wherein thereis illustrated a preferred film unit of the present invention andwherein like numbers, appearing in the various figures, refer to likecomponents.

As illustrated in the drawings, FIG. 1 sets forth a perspective view ofthe film unit, designated 10, and each of FIGS. 2 through 7 illustratediagrammatic cross-sectional views of film unit 10, along the statedsection lines 2-2. 33, 5-5, and 7-7, during the various depicted stagesin the performance of a photographic diffusion transfer process asdetailed hereinafter.

Film unit comprises rupturable container 11, retaining, prior toprocessing, aqueous alkaline solution 12, and photosensitive laminate 13including, in order, dimensionally stable opaque layer 14, preferably anactinic radiation-opaque flexible sheet material; cyan dye developerlayer 15; red-sensitive silver halide emulsion layer 16; interlayer 17;magenta dye developer layer 18; green-sensitive silver halide emulsionlayer 19; interlayer 20; yellow dye developer layer 21; bluesensitivesilver halide emulsion layer 22; auxiliary layer 23, which may containan auxiliary silver halide developing agent; reflecting agent precursorlayer image-receiving layer 24; and dimensionally stable transparentlayer 27, preferably an actinic radiation transmissive flexible sheetmaterial.

The structural integrity of laminate 13 may be maintained, at leastinpart, by the adhesive capacity exhibited between the various layerscomprising the laminate at their opposed surfaces. However, the adhesivecapacity exhibited at an interface intermediate image-receiving layer 24and the silver halide emulsion layer next adjacent thereto, for example,reflecting agent precursor intermediate layer 25 and auxiliary layer 23as illustrated in FIGS. 2 through 7, should be less than that exhibitedat the interface between the opposed surfaces of the remainder of thelayers forming the laminate in order to facilitate distribution ofprocessing solution 12 intermediate the stated image-receiving layer 24and the silver halide emulsion layer next adjacent thereto. Thelaminates structural integrity may also be enhanced or provided, inwhole or in part, by providing a binding member extending around, forexample, the edges of laminate l3, and maintaining the layers comprisingthe laminate intact, except at the interface between layers 23 and 24during distribution of alkaline solution 12 intermediate those layers.As illustrated in the figures, the binding member may comprise apressure-sensitive tape 28 securing and/or maintaining the layers oflaminate 13 together at its respective edges. Tape 28 will also act tomaintain processing solution 12 intermediate image-receiving layer 24and the silver halide emulsion layer next adjacent thereto, uponapplication of compressive pressure to pod 11 and distribution of itscontents intemiediate the stated layers. Under such circumstances,binder tape 28 will act to prevent leakage of fluid processingcomposition from the film units laminate during and subsequent tophotographic processing.

Rupturable container 11 may be of the type shown and described in any ofU.S. Pat. Nos. 2,543,181; 2,634,886; 3,653,732; 2,723,051; 3,056,492;3,056,491; 3,152,515; and the like. In general, such containers willcomprise a rectangular blank of fluidand air-impervious sheet materialfolded longitudinally upon itself to form two walls 29 which are sealedto one another along their longitudinal and end margins to form a cavityin which processing solution 12 is retained. The longitudinal marginalseal 30 is made weaker than the end seals 31 so as to become unsealed inresponse to the hydraulic pressure generated within the fluid contents12 of the container by the application of compressive pressure to walls29 of the container.

As illustrated in FIGS. 1, 2 and 4, container 11 is fixedly positionedand extends transverse a leading edge of photosensitive laminate 13whereby to effect unidirectional discharge of the containers contents 12between image-receiving layer 24 and the stated layer next adjacentthereto, upon application of compressive force to container 11. Thus,container 11, as illustrated in FIG. 2, is fixedly positioned andextends transverse a leading edge of laminate 13 with its longitudinalmarginal seal 30 directed toward the interface between imagereceivinglayer 24 and auxiliary layer 23. As shown in FIGS. 1, 2 and 4, container11 is fixedly secured to laminate 13 by extension 32 of tape 28extending over a portion of one wall 29 of the container, in combinationwith a separate retaining member such as illustrated retaining tape 33extending over a portion of the other wall 29 of the container and aportion of laminate 13s surface generally equal in area to about thatcovered by tape 28.

As illustrated in FIG. 6, extension flap 32 of tape 28. is preferably ofsuch area and dimensions that upon, for example, manual separation ofcontainer 11 and tape 33, subsequent to distribution of processingcomposition 12, from the remainder of film unit 10, flap 32 may befolded over the edge of laminate 13, previously covered by tape 33, inorder to facilitate maintenance of the laminate's structural integrity,for example, during the flexations inevitable in storage and use of theprocessed film unit, and to provide a suitable mask or frame, forviewing of the transfer image through the picture viewing area oftransparent layer 27.

The fluid contents of the container comprise an aqueous alkalinesolution having a pH and solvent concentration at which the dyedevelopers are soluble and diffusible and contains an opacifying agentin a quantity sufficient, upon distribution, effective to preventexposure of photosensitive silver halide emulsion layers 16, 19 and 22by actinic radiation incident on dimensionally stable transparent layer27 during processing in the presence of such radiation. Accordingly, thefilm unit may be processed, subsequent to distribution of thecomposition, in the presence of such radiation, in view of the fact thatthe silver halide emulsion or emulsions of laminate are appropriatelyprotected by incident radiation, at one major surface of the opaqueprocessing composition and at the remaining major surface by thedimensionally stable opaque layer. If the illustrated binder tapes arealso opaque, edge leakage of actinic radiation incident on the emulsionor emulsions will also be prevented.

The selected reflecting agent generated, however, should be oneproviding a background suitable for viewing the dye developer transferimage formed in the dyeable polymeric layer. In general, whilesubstantially any reflecting agent may be employed, it is preferred thata reflecting agent be selected that will not interfere with the colorintegrity of the dye transfer image, as viewed by the observer, and,most preferably, an agent which is aesthetically pleasing to the viewerand does not provide a background noise signal degrading, or detractingfrom, the information content of the image. Particularly desirablereflecting agents will be those providing a white background, forviewing the transfer image, and specifically those conventionallyemployed to provide background for reflection photographic prints and,especially those agents possessing the optical properties desired forreflection of incident radiation.

As examples of preferred reflecting agent precursors adapted foremployment in the practice of the present invention mention may be madeof ionizable, white, inorganic, visible light reflecting pigmentgenerating salts such as barium chloride, zirconium chloride, and thelike, the cation of which upon contact with sulfate ions present in theselected processing composition and generally derived from ionizablesalts such as sodium sulfate, etc., form reflecting agent pigment saltssuch as barium sulfate, zirconium sulfate, and the like; ionizable saltssuch as zinc sulfate and the like, the cation of which upon contact theanion of ionized sodium or potassium hydroxide present in the selectedprocessing composition fonn reflecting agent pigment such as zinc oxideand the like; ionizable salts such as zinc acetate and the like, thecation of which upon contact with sulfide ions present in the selectedprocessing compositions and generally derived from ionizable salts suchas sodium sulfide, etc., form reflecting agent such zinc sulfide and thelike; etc. It will be recognized that where desired the functionalcation of the exemplary materials may optionally be disposed in theprocessing composition employed and the anion initially disposed in theprocessing composition permeable layer; that such adjuncts as aredisclosed as initially disposed in the processing compositionaltematively may be selectively disposed within the film unit insulatedfrom functional generation of the reflecting agent preceding exposure ofthe film unit, for example, preceding processing compositionsolubilization of such adjunct and/or required diffusion and contactbetween the reactants intermediate the image-receiving layer and nextadjacent photosensitive silver halide emulsion layer; and thatreflecting agent may be in part generated within the image-receivingand/or next adjacent silver halide emulsion strata of the film unit.

A particularly preferred embodiment of the present invention employs ametathetical reaction between selected precursor salts, the respectiveexchange of cations or anions of which provide for the simultaneousgeneration of two separate reflecting agents such as, for example, themetathetical generation of both barium sulfate and zinc sulfide white,inorganic salt pigments by the in situ reaction of substantiallycolorless barium sulfide and zinc sulfate precursor salts. Suchpreferred embodiments provide for the in process generation of anincreased quantity of reflecting agent per unit volume of precursorsalts employed.

A particularly preferred reflecting agent comprises barium sulfate dueto its highly effective reflection properties.

In general, in the preferred embodiments, the reflecting agent precursorselected will, as previously denoted, comprise a precursor specificallyadapted to provide a substantially white inorganic pigment whichreflects visible light and, in particularly preferred embodiments, willbe coated at a coverage effective to provide 200 to 1,000 mgs./ft.reflecting agent, as a result of processing, which coverage is generallysufficient, subsequent to processing, to mask opacifying agentdistributed in the processing composition and any residual dye developerpresent intermediate the image-receiving layer and the dimensionallystable opaque layer.

Where desired, reflecting agent precursor or precursors may bedistributed in whole or in part within a processing compositionpermeable polymeric matrix such as gelatin and/or any other suchpolymeric matrixes as are specifically denoted throughout thespecification as suitable for employment as a matrix binder and may bedistributed in one or more of the film unit layers which may beseparated or contiguous and should be intermediate the image-receivinglayer and dimensionally stable opaque layer, provided that itsdistribution and concentration is effective to provide the denoted postprocessing masking function, and that in whole or in part the resultant[generated reflecting agent may be ultimately disposed within theprocessing composition residuum located intermediate the image-receivinglayer and next adjacent silver halide emulsion strata and associated dyeimage-forming material.

As examples of opacifying agents adapted for employment in the practiceof the present invention, mention may be made of opacifying pigments andopacifying dyes and mixtures of such dyes and/r pigments preferably dyesand pigments of black coloration and most preferably black pigments suchas carbon black, iron oxide, titanium (Ill) oxide, titanium (Ill)hydroxide, and the like.

Preferred opacifying agent or agents will possess the maximum opacifyingcapacity per unit weight, be photographically nondeleterious andsubstantially nondiffusible during and subsequent to distribution of theprocessing composition containing same. A particularly preferredopacifying agent has been found to comprise carbon black due to itshighly efficient absorption characteristics. in general, a processingcomposition particularly desired for employment in the practice of thepresent invention will contain carbon black in a concentrationefiective, e.g., about 3 to 20 grams of carbon black dispersed in 100cc. of water, to prevent transmission, through the distributed stratumcomprising the composition, of in excess of 95 percent of the actinicradiation incident on the stratum.

In general, preferred agents, both opacifying and reflecting, are thosewhich remain immobile within their respective compositions during andsubsequent to photographic processing and particularly those whichcomprise insoluble and nondiffusible pigment dispersions.

In the performance of a diffusion transfer multicolor process employingfilm unit 10, the unit is exposed to radiation, actinic tophotosensitive laminate l3, incident on the laminate s exposure surface34, as illustrated in FIG. 2.

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit 10 isprocessed by being passed through opposed suitably gapped rolls 35 inorder to apply compressive pressure to frangible container 11 and toeffect rupture of longitudinal seal 30 and distribution of alkalineprocessing composition 12, possessing an opacifying agent and a pH atwhich the cyan, magenta and yellow dye developers are soluble anddiffusible as a function of the point-to-point degree of exposure ofredsensitive silver halide emulsion layer 16, green-sensitive silverhalide emulsion layer 19 and blue-sensitive silver halide emulsion layer22, respectively, intermediate reflecting agent precursor layer 25 andauxiliary layer 23.

Alkaline processing solution 12 permeates emulsion layers 16, 19 and 22to initiate development of the latent images contained in the respectiveemulsions and reflecting agent precursor layer 25 to initiate generationof reflecting agent. The cyan, magenta and yellow dye developers, oflayers 15, 18 and 21, are immobilized, as a function of the developmentof their respective associated silver halide emulsions, preferablysubstantially as a result of their conversion from the reduced form totheir relatively insoluble and nondiffusible oxidized form, therebyproviding imagewise distributions of mobile, soluble and diffusiblecyan, magenta and yellow dye developer, as a function of thepoint-to-point degree of their associated emulsions exposure. At leastpart of the imagewise distributions of mobile cyan, magenta and yellowdye developer transfers, by diffusion, to dyeable polymeric layer 24 toprovide a multicolor dye transfer image to that layer which is viewableagainst the background provided by the in situ generated reflectingagent layer 26 which layer effects masking of opacifying agent presentin processing composition residuum l2 and cyan, magenta and yellow dyedeveloper remaining associated with blue-sensitive emulsion layer 22,greensensitive emulsion layer 19 and red-sensitive emulsion layer 16.

Subsequent to distribution of processing solution 12, container 11 maybe manually dissociated from the remainder of the film unit, as.described above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed inconjunction with the following illustrative constructions which set outrepresentative embodiments and photographic utilization of the novelphotographic film units of this invention, which, however, are notlimited to the details therein set forth and are intended to beillustrative only.

Film unit similar to that shown in the drawings may be prepared, forexample, by coating, in succession, on a gelatin subbed, 4 mil. opaquepolyethylene terephthalate film base, the following layers:

1. a layer of the cyan dye developer1,4-bis-(B-[hydroquinonyl-a-methyl]-ethylamino)-5,8-dihydroxy-anthraquinonedispersed in gelatin and coated at a coverage of about 150 mgs./ft. ofdye and about 200 mgs./ft. of gelatin;

2. a red-sensitive gelatinosilver iodobromide emulsion coated at acoverage of about 200 mgs./ft. of silver and about mgs./ft. of gelatin;

3. a layer of gelatin coated at a coverage of about 200 mgs./ft.

4. a layer of the magenta dye developerZ-(p-[fi-hydroquinonylethyl]-phenylazo)-4-isopropoxyl -naphtholdispersed in gelatin and coated at a coverage of 70 mgs./ft. of dye andabout 100 mgs./ft. of gelatin;

5. a green-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about 100 mgs./ft. of silver and 60 mgsJft. of gelatin;

6. a layer containing 4-methylphenyl hydroquinone dispersed in gelatinand coated at a coverage of about 25 mgsJft. of 4-methyl-phenylhydroquinone and about mgsJft. of gelatin;

7. a layer of the yellow dye developer4-(p-[B-hydroquinonylethyl]-phenylazo)-3-(N,n-hexylcarboxamido)-nlphenyl-S-pyrazolonedispersed in gelatin and coated at a coverage of about 40 mgs./ft. ofdye and 50 mgs./ft. of gelatin;

8. a blue'-sensitive gelatino-silver iodobromide emulsion coated at acoverage of about 60 mgsJft. of silver and about 50 mgslft. of gelatin;and

9. a layer of gelatin coated at a coverage of about mgs./ft. of gelatin.

Then a transparent 4 mil. polyethylene terephthalate film base may becoated, in succession, with the following illustrative layers:

1. the partial butyl ester of polyethylene/maleic anhydride copolymerprepared by refluxing, for 14 hours, 300 grams of high viscositypoly-(ethylene/maleic anhydride), 140 grams of n-butyl alcohol and 1 cc.of 85 percent phosphoric acid to provide a polymeric acid layerapproximately 0.75 mils. thick;

2. a 2:1 solution of hydroxypropyl cellulose and polyvinyl alcohol inwater to provide a polymeric spacer layer approximately 0.25 mil. thick;

3. a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of approximately 600 mgs./ft. to provide apolymeric image-receiving layer approximately 0.40 mil. thick; and

. a dispersion of barium chloride in gelatin at a coverage ofapproximately 900 mgs./ft. barium chloride and of approximately 150mg./ft. gelatin to provide a polymeric reflecting agent precursor layerapproximately 0.25 mil. thick.

The two components thus prepared may then be taped together in laminateform, at their respective edges, by means of a pressure-sensitivebinding tape extending around, in contact with, and over the edges ofthe resultant laminate.

A rupturable container comprising an outer layer of lead foil and aninner liner or layer of polyvinyl chloride retaining an aqueous alkalineprocessing solution comprising:

may then be fixedly mounted on the leading edge, of each of thelaminates, by pressure-sensitive tapes interconnecting the respectivecontainers and laminates, such that upon application of compressivepressure to a container its contents would be distributed, upon ruptureof the containers marginal seal, between layer 9 and the polymericreflecting layer.

The photosensitive laminates may then be exposed through step wedges toselectively filtered radiation incident to the transparent polyethyleneterephthalate layer and initially processed, in the absence of actinicradiation, by passage of the exposed film unit through suitably gappedopposed rolls, to effect rupture of the container and distribution ofits contents. During processing, the multicolor dye transfer imageformation may be viewed through the transparent polyethyleneterephthalate film base against the in situ generated barium sulfatereflecting agent and such image for mation is found to be substantiallycompleted and exhibiting the required color brilliance, hues,saturation, stability and isolation, within a period of approximately 90seconds.

As an illustrative construction of the novel film units of the presentinvention employing the aforementioned metathetical generation ofreflecting agent in situ, the barium chloride precursor of layer 4immediately above may be replaced with a dispersion of barium sulfide ingelatin coated, as above, at an average of approximately 725 mgs./ft.barium sulfide and of approximately 150 mgs./ft. gelatin and the sodiumsulfate precursor of the processing composition may be replaced with12.2 grams of zinc sulfate to effectively provide the simultaneous insitu generation of both barium sulfate and zinc sulfide reflecting agentpigments, intermediate the image-receiving layer of the film unit andauxiliary layer 9, during processing of a photoexposed film unit.

The pH and solvent concentration of the alkaline processing solutioninitially employed must be an alkaline pH at which the dye developersemployed are soluble and diffusible. Although it has been found that thespecific pH to be employed may be readily determined empirically for anydye developer, or group of dye developers, most particularly desirabledye developers are soluble at pHs above 9 and relatively insoluble atpH's below 9, in reduced form, and relatively insoluble at substantiallyany alkaline pH, in oxidized form, and the system-can be readilybalanced accordingly for such dye developers. In addition, although aspreviously noted, the processing composition, in the preferredembodiment, will include the stated film-forming viscosity-increasingagent, or agents, to facilitate spreading of the composition and toprovide maintenance of the spread composition as a structurally stablelayer of the laminate, subsequent to distribution, it is not necessarythat such agent be employed as a component of the composition.

Where desired, a polymeric acid layer, for example, of the typediscussed above, may be additionally incorporated, as stated, in thefilm unit of the present invention, to provide reduction of thealkalinity of the processing solution from a pH at which the dyes aresoluble to a pH at which the dyes are substantially nondiffusible, inorder to advantageously further stabilize the dye transfer image. Insuch instance, the polymeric acid layer may be positioned intermediatethe transparent support and image-receiving layer, and/or the opaquesupport and next adjacent emulsion/dye unit layer, and the film unit mayalso contain a polymeric spacer or barrier layer next adjacent thepolymeric acid layer, opposite the respective sup port layer, aspreviously described.

As disclosed in aforementioned US. Pat. No. 3,362,819, the presence ofan inert spacer layer was found to be effective in evening out thevarious reaction rates over a wide range of temperatures, for example,by preventing premature pH reduction when imbibition is effected attemperatures above room temperature, for example, at to F. By providingan inert spacer layer, that application discloses that the rate at whichalkali is available for capture in the polymeric acid layer becomes afunction of the alkali diffusion rates.

However, as disclosed in copending US; Pat. application Ser. No.664,503, filed Aug. 30, 1967 in the names of Leonard C. Farney, HowardG. Rogers and Richard W. Young, now U.S. Pat. No. 3,455,686, issued July15, 1969 preferably the aforementioned rate at which the cations of thealkaline processing composition, i.e., alkali ions, are available forcapture in the polymeric acid layer should be decreased with increasingtransfer-processing temperatures in order to provide diffusion transfercolor processes relatively independent of positive transfer imagevariations over an extended range of ambient temperatures.

Specifically, it is there state to have been found that the diffusionrate of alkali through a permeable inert polymeric spacer layerincreases with increased processing temperature to the extent, forexample, that at relatively high transferprocessing temperatures, thatis, transfer-processing temperatures above approximately 80 F., apremature decrease in the pH of the transfer processing compositionoccurs due, at least in part, to the rapid diffusion of alkali from thedye transfer environment and its subsequent neutralization upon contactwith the polymeric acid layer. This was stated to be especially true ofalkali traversing an inert spacer layer possessing permeability toalkali optimized to be effective within the temperature range of optimumtransfer processing. Conversely, at temperatures below the optimumtransfer processing range, for example, temperatures below approximately40 F., the last-mentioned inert spacer layer was disclosed to provide aneffective diffusion barrier timewise preventing effective traverse ofthe inert spacer layer by alkali having temperature depressed ditfusionrates and to result in maintenance of the transfer processingenvironments high pH for such an extended time interval as to facilitateformation of transfer image stain and its resultant degradation of thepositive transfer images color definition.

lt is further stated in the last-mentioned copending application Ser.No. 664,503 to have been found, however, that if the inert spacer layerof the print-receiving element is replaced by a spacer layer whichcomprises a permeable polymeric layer exhibiting permeability inverselydependent on temperature, that is, a polymeric film-forming materialwhich exhibits decreasing permeability to solubilized alkali derivedcations such as alkali metal and quanternary ammonium ions underconditions of increasing temperature, that the positive transfer imagedefects resultant from the aforementioned overextended pH maintenanceand/or premature pl-l reduction are obviated.

As examples of polymers which were disclosed to exhibit inversetemperature dependent permeability to alkali, mention may be made of:hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethyleneoxide, polyvinyl oxazolidone, hydroxypropyl methyl cellulose, iospropylcellulose, partial acetals of polyvinyl alcohol such as partialpolyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal,partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated togenerally comprise saturated aliphatic hydrocarbon chains of a molecularweight of at least 1,000, preferably of about 1,000 to 50,000 possessinga degree of acetalation within about 10 to 30 percent, 10 to 30 percent,to 80 percent, and 10 to 40 percent, of the polyvinyl alcoholstheoretical polymeric hydroxy groups, respectively, and including mixedacetals where desired.

Where desired, a mixture of the polymers is to be employed, for example,a mixture of hydroxypropyl methyl cellulose and partial polyvinylbutyral.

Employment of the detailed and preferred film units of the presentinvention, according to the herein described color diffusion transferprocess, specifically provides for the production of a highly stabletransfer image accomplished, at least in part, by effectively obviatingthe previously discussed disadvantages of the prior art products andprocesses, by in process adjustment of the environmental processingconditions from those at which dye diffusion or transfer is operative toconditions at which dye transfer is inoperative subsequent tosubstantial transfer image formation. The stable color transfer image isobtained irrespective of the fact that the film unit is maintained as anintegral laminate unit during exposure, processing, viewing, and storageof the unit. Accordingly, by means of the present invention, multicolortransfer images may be. provided over an extended processing temperaturerange which exhibit desired maximum and minimum dye transfer imagedensities; yellow, magenta and cyan dye saturation; red, green and bluehues; and color separation. These unexpected advantages are in additionto the manufacturing advantages obtained by reason of the presentinventions integral color transfer film unit and which will be readilyapparent from examination of the units parameters, that is, for example,advantages in more efficient utilization of fabricating materials andcomponents, enhanced simplicity of film manufacture and camera designand construction, and more simplified and effectively controlledcustomer utilization of the unit.

The dimensionally stable support layers referred to may comprise any ofthe various types of conventional opaque and transparent rigid orflexible materials possessing the requisite liquid impermeability andvapor transmissivity denoted above, and may comprise polymeric films ofboth synthetic types and those derived from naturally occurringproducts. Particularly suitable materials include aqueous alkalinesolution impermeable, water vapor permeable, flexible polymericmaterials such as vapor permeable polymeric films derived from ethyleneglycol terephthalic acid, vinyl chloride polymers;

polyvinyl acetate; polyamides; polymethacrylic acid methyl and ethylesters; cellulose derivatives such as cellulose, acetate, triacetate,nitrate, propionate, butyrate, acetatepropionate, or acetate-butyrate;alkaline solution impermeable, water vapor permeable papers;cross-linked polyvinyl a1- cohol; regenerated cellulose; and the like.

It will be noted that the liquid processing composition employed maycontain an auxiliary or accelerating developing agent, such asp-methylaminophenol, 2,4-diamino-phenol, pbenzylaminophenyl,hydroquinone, toluhydroquinone, phenylhydroquinone,4'-methylphenylhydroquinone, etc. It is also contemplated to employ aplurality of auxiliary or accelerating developing agents, such as aB-pyrazolidone developing agent and a benzenoid developing agent, asdisclosed in US. Pat. No. 3,039,869, issued June 19, 1962. As examplesof suitable combinations of auxiliary developing agents, mention may bemade of 1-phenyl-3-pyrazolidone in combination with pbenzylaminophenoland l-phenyl-3-pyrazolidone in combination with 2,5-bis-ethylenimino-hydroquinone. Such auxiliary developing agents may be employed in theliquid processing composition or they may be initially incorporated, atleast in part, in any one or more of the silver halide emulsion strata,the strata containing the dye developers, the interlayers, the overcoatlayer, the image-receiving layer, or in any other auxiliary layer, orlayers, of the film unit. It may be noted that at least a portion of thedye developer oxidized during development may be oxidized andimmobilized as a result of a reaction, e.g., an energy-transferreaction, with the oxidation product of an oxidized auxiliary developingagent, the latter developing agent being oxidized by the development ofexposed silver halide. Such a reaction of oxidized developing agent withunoxidized dye developer would regenerate the auxiliary developing agentfor further reaction with the exposed silver halide.

ln addition, development may be effected in the presence of an oniumcompound, particularly a quaternary ammonium compound, in accordancewith the processes disclosed in U.S. Pat. No. 3,173,786, issued Mar. 16,1965.

It will be apparent that the relative proportions of the agents of thediffusion transfer-processing composition may be altered to suit therequirements of the operator. Thus, it is within the scope of thisinvention to modify the herein described developing compositions by thesubstitution of preservatives, alkalies, etc., other than thosespecifically mentioned, provided that the pH of the composition isinitially at the first pH and solvent concentration required. Whendesirable, it is also contemplated to include, in the developingcomposition, components such as restrainers, accelerators, etc.Similarly, the concentration of various components may be varied over awide range and when desirable adaptable components may be disposed inthe photosensitive element, prior to exposure, in a separate permeablelayer of the photosensitive element and/or in the photosensitiveemulsion.

In all examples of this specification, percentages of components aregiven by weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adaptedfor employment in photographic diffusion transfer processes is set forthin aforementioned US. Pat. No. 2,983,606 and in the various copendingUS. applications referred to in that patent, especially in the table ofUS. applications incorporated by reference into the patent as detailedin column 27. As examples of additional US. patents detailing specificdye developers for photographic transfer process use, mention may alsobe made of US. Pat. Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808;3,076,820; 3,077,402, 3,126,280; 3,131,061,; 3,134,762; 3,134,765;3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; andthe like.

As additional examples of synthetic, film-forming, permeable polymersparticularly adapted to retain dispersed dye developer, mention may bemade of nitrocarboxymethyl cellulose, as disclosed in US. Pat. No.2,992,104; an acylamidobenzene sulfo ester of a partial sulfobenzal ofsaturated carboxylic acids, as disclosed in U.S. Pat. No.

3,069,264; and the like.

In addition to conventional techniques for the direct dispersion of aparticulate solid material in a polymeric, or colloidal, matrix such asball milling and the like techniques, the

preparation of the dye developer dispersion may also be obtained bydissolving the dye in an appropriate solvent, or mixture of solvents,and the resultant solution distributed in the polymeric binder, withoptional subsequent removal of the solvent, or solvents, employed, as,for example, by vaporization where the selected solvent, or solventspossesses a sufficiently low boiling point or washing where the selectedsolvent, or solvents, possesses a sufficiently high differentialsolubility in the wash medium, for example, water, when measured againstthe solubility of the remaining composition components, and/or obtainedby dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of thetypes referred to above, and for an extensive compilation of theconventional solvents traditionally employed in the art to effectdistribution of photographic colorproviding materials in polymericbinders, specifically for the formation component layers of photographicfilm units, reference may be made to U.S. Pat. Nos. 2,269,158;2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

Although the invention has been discussed in detail throughout employingdye developers, the preferred dye image-providing materials, it will bereadily recognized that other, less preferred, dye image-providingmaterials may be substituted in replacement of the preferred dyedevelopers in the practice of the invention. For example, there may beemployed dye image-forming materials such as those disclosed in U.S.Pat. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735;3,148,062; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294;3,330,655; 3,347,671; 3,352,672; 3,364,022; 3,443,939; 3,443,940;3,443,941; 3,443,943; etc., wherein color diffusion transfer processesare described which employ color coupling techniques comprising, atleast in part, reacting one or more color-developing agents and one ormore color formers or couplers to provide a dye transfer image to asuperposed image-receiving layer and those disclosed in U.S. Pat. No.2,774,668 and 3,087,817, wherein color diffusion transfer processes aredescribed which employ the irnagewise differential transfer of completedyes by the mechanisms therein described to provide a transfer dye imageto a contiguous image-receiving layer, and thus including the employmentof image-providing materials in whole or in part initially insoluble ornondiffusible as disposed in the film unit which diffuse duringprocessing as a direct or indirect function of exposure.

For the production of the photosensitive gelatino silver halideemulsions employed to provide the film unit, the silver halide crystalsmay be prepared by reacting a water-soluble silver salt, such as silvernitrate, with at least one water-soluble halide, such as ammonium,potassium or sodium bromide, preferably together with a correspondingiodide, in an aqueous solution of a peptizing agent such as a colloidalgelatin solution; digesting the dispersion at an elevated temperature,to provide increased crystal growth; washing the resultant dispersion toremove undesirable reaction products and residual water-soluble salts bychilling the dispersion, noodling the set dispersion, and washing thenoodles with cold water, or alternatively, employing any of the variousflocc systems, or procedures, adapted to effect removal or undesiredcomponents, for example, the procedures described in U.S. Pat. Nos.2,614,928; 2,614,929; 2,728,662; and the like; after ripening thedispersion at an elevated temperature in combination with the additionof gelatin and various adjuncts, for example, chemical sensitizingagents of U.S. Pat. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856;2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all accordingto the traditional procedures of the art, as described in Neblette, C.3., Photography Its Materials and Processes, 6th Ed., 1962.

Optical sensitization of the emulsions silver halide crystals may beaccomplished by contact of the emulsion composition with an effectiveconcentration of the selected optical sensitizing dyes dissolved in anappropriate dispersing solvent such as methanol, ethanol, acetone,water, and the like; all according to the traditional procedures of theart, as described in Hammer, F. M., The Cyanine Dyes and RelatedCompounds.

Additional optional additives, such as coating aids, hardeners,viscosity-increasing agents, stabilizers, preservatives, and the like,for example, those set forth hereinafter, also may be incorporated inthe emulsion formulation, according to the conventional procedures knownin the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, aspreviously described, preferably comprise a crystal of silver, forexample, one or more of the silver halides such as silver chloride,silver iodide, silver bromide, or mixed silver halides such as silverchlorobromide or silver iodobromide, of varying halide ratios andvarying silver concentrations.

As the binder for the respective emulsion strata, the aforementionedgelatin may be, in whole or in part, replaced with some other colloidalmaterial such as albumin; casein; or zein; or resins such as a cellulosederivative, as described in U.S. Pat. Nos. 2,322,085 and 2,327,808;polyacrylamides, as described in U.S. Pat. No. 2,541,474; vinyl polymerssuch as described in an extensive multiplicity of readily available U.S.and foreign patents.

Although the preceding description of the invention has been couched interms of the preferred photosensitive component construction wherein atleast two selectively sensitized photosensitive strata are in contiguouscoplanar relationship and, specifically, in terms of the preferredtripack-type structure comprising a red-sensitive silver halide emulsionstratum, a green-sensitive silver halide emulsion stratum and abluesensitive silver halide emulsion stratum having associatedtherewith, respectively, a cyan dye developer, a magenta dye developerand a yellow dye developer, the photosensitive component of the filmunit may comprise at least two sets of selectively sensitized minutephotosensitive elements arranged in the form of a photosensitive screenwherein each of the minute photosensitive elements has associatedtherewith, for example, an appropriate dye developer in or behind itsrespective silver halide emulsion portion. in general, a suitablephotosensitive screen will comprise minute red-sensitized emulsionelements, minute green-sensitized emulsion elements and minuteblue-sensitized emulsion elements arranged in side-by-side relationshipin a screen pattern and having associated therewith, respectively, acyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dyedeveloper and the use of a mixture of dye developers adapted to providea black and white transfer image, for example, the employment of dyedevelopers of the three subtractive colors in an appropriate mixture inwhich the quantities of the dye developers are proportioned such thatthe colors combine to provide black.

Where in the specification, the expression positive image" has beenused, this expression should not be interpreted in a restrictive sensesince it is used primarily for purposes of illustration, in that itdefines the image produced on the imagecarrying layer as being reversed,in the positive-negative sense, with respect to the image in thephotosensitive emulsion layers. As an example of an alternative meaningfor positive image, assume that the photosensitive element is exposed toactinic light through a negative transparency. In this case, the latentimage in the photosensitive emulsion layers will be a positive and thedye image produced on the image-carrying layer will be a negative. Theexpression positive image" is intended to cover such an image producedon the image-carrying layer.

It will be recognized that, by reason of the preferred film unit'sstructural parameters, the transfer image formed upon direct exposure ofthe film unit to a selected subject and processing, will be ageometrically reversed image of the subject. Accordingly, to providetransfer image formation geometrically nonreversed, exposure of suchfilm unit should be accomplished through an image reversing opticalsystem such a camera possessing an image reversing optical system.

In addition to the described essential layers, it will be recognizedthat the film unit may also contain one or more subcoats or layers,which, in turn, may contain one or more additives such as plasticizers,intermediate essential layers for the purpose, for example, of improvingadhesion, and that any one or more of the described layers may comprisea composite of two or more strata of the same, or different, componentsand which may be contiguous, or separated from, each other, for example,two or more neutralizing layers or the like, one of which may bedisposed intermediate the cyan dye image-forming componentretaininglayer and the dimensionally stable opaque layer.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and notin a limiting sense.

What is claimed is:

1. In a photographic film unit which comprises, in combination:

a photosensitive element including a composite structure containing, asessential layers, in sequence, a first dimensionally stable, liquidimpermeable layer opaque to incident actinic radiation; a photosensitivesilver halide layer having associated therewith a dye image-formingmaterial which is processing composition soluble and diffusible, as afunction of exposure of the photosensitive silver halide emulsion layerto incident actinic radiation; a polymeric layer dyeable by said. dyeimage-providing material; a second dimensionally stable, liquidimpermeable layer transparent to incident actinic radiation, and meanssecuring said layers in substantially fixed relationship; and means fordistributing a processing composition between said dyeable polymericlayer and the photosensitive silver halide emulsion layer next adjacentthereto;

the improvement which comprises a layer permeable to processingcomposition solubilized dye image-forming material which comprises lightreflecting agent precursor which includes, upon contact with aprocessing composition, first ionic species adapted to interact withsecond ionic species to provide a substantially white, inorganic visiblelight reflecting agent intermediate said dyeable polymeric layer andsaid photosensitive silver halide layer.

2. A photographic film unit as defined in claim ll wherein saidreflecting precursor is present in a quantity sufficient to provide,upon contact with said processing composition, said substantially white,inorganic visible light reflecting agent effective to mask said dyeimage-forming material associated with said photosensitive silver halidelayer subsequent to processing.

3. A photographic film unit as defined in claim 1 wherein said means fordistributing a processing composition comprises container means fixedlypositioned extending transverse a leading edge of said photosensitiveelement to effect unidirectional discharge of said containers processingcomposition between said layer containing said reflecting agentprecursor and the photosensitive silver halide layer next adjacentthereto and said processing composition contains an opacifying agent ina quantity suificient upon distribution between said layer containingsaid reflecting agent precursor and the photosensitive silver halidelayer next adjacent thereto to prevent exposure of said silver halidelayer in the presence of actinic radiation incident on saiddimensionally stable transparent layer.

4. A photographic film unit as defined in claim 3 wherein saidreflecting agent precursor is present in a quantity sufficient uponconversion to reflec,ing agent to mask said distributed opacifying agentsubsequent to processing.

5. A photographic film unit as defined in claim 4, wherein said dyeimage-providing material is a dye which is a silver halide developingagent.

6. A photographic film unit as defined in claim 5 wherein saidopacifying agent is carbon black.

'7. A photographic film unit as defined in claim 6 wherein said carbonblack is present in said processing composition in a concentrationwithin the range of about 3 to 20 grams of carbon black per cc. ofprocessing composition.

8. A photographic film unit as defined in claim 5 wherein said aqueousalkaline solution contains a film-forming polymeric material.

9. A photographic film unit as defined in claim 8 wherein saidreflecting agent precursor is barium ions and said processingcomposition contains sulfate ions adapted to react with said barium ionsto provide substantially white, inorganic, visible light reflectingbarium sulfate pigment.

10. A photographic film unit as defined in claim 9 wherein said bariumions and said sulfate ions are present in substantially stoichiometricquantities sufficient to provide a barium sulfate coverage of from about200 to 1,000 mgs./ft. reflecting agent.

111. A photographic film unit as defined in claim 5 wherein saidreflecting agent precursor is disposed in a polymeric matrix permeableto processing composition solubilized dye.

12. A photographic film unit as defined in claim 11 wherein saidpolymeric matrix is gelatin.

13. A photographic film unit as defined in claim 5 wherein saidphotosensitive element comprises at least two selectively sensitizedsilver halide emulsion layers each having a dye which dye is a silverhalide developing agent of predetermined color associated therewith,each of said dyes soluble and diffusible in alkaline processingcomposition as a function of the point-to point degree of exposure ofthe respective emulsion associated therewith.

M. A photographic film unit as defined in claim 13 wherein each of saidselectively sensitized photosensitive silver halide emulsions haspredominant spectral sensitivity to separate regions of the spectrum andthe dye associated with each of said silverhalide emulsion layerspossesses a spectral absorption range subsequent to processingsubstantially complementary to the predominant sensitivity range of itsassociate emulsion layer.

15. A photographic film unit as defined in claim 14 wherein each of saidsilver halide emulsion layers and its associated dye is separated fromthe next adjacent silver halide emulsion layer and its associated dye byan alkaline solution permeable polymeric interlayer.

16. A photographic film unit as defined in claim 4 wherein saidprocessing composition is an aqueous alkaline processing composition andsaid film unit additionally contains at least one acidic layerpositioned intermediate at least one of said dimensionally stable opaquelayer and the photosensitive silver halide emulsion layer next adjacentthereto, and said dimensionally stable transparent layer and the dyeablepolymeric layer next adjacent thereto.

17. A photographic film unit as defined in claim 16 wherein said acidiclayer comprises a polymeric acid layer containing sufficient acidifyinggroups to effect reduction of said processing solution from a first pHat which said dye is substantially soluble and diffusible to a second pHat which said dye is substantially nondiffusible.

18. In a photographic film unit as defined in claim 17 which is adaptedto be processed by passing said unit between a pair of juxtaposedpressure-applying members and which comprises, in combination, acomposite structure containing, as essential layers, in sequence, adimensionally stable, liquid impermeable opaque layer; an alkalinesolution permeable polymeric layer containing cyan dye; a red-sensitivesilver halide emulsion layer; an alkaline solution permeable polymericlayer containing magenta dye; a green-sensitive silver halide emulsionlayer; an alkaline solution permeable polymeric layer containing yellowdye; a blue-sensitive silver halide emulsion layer, each of said cyan,magenta and yellow dyes being silver halide developing agents and beingsoluble and diffusible in an aqueous alkaline solution at a first pH; analkaline solution permeable transparent polymeric layer dyeable by saiddyes; an alkaline solution permeable transparent polymeric acid layercontaining sufficient acidifying groups to effect reduction of aprocessing solution having said first pH to a second pH at which saiddyes are substantially nondiffusible;

a dimensionally stable, liquid impermeable transparent layer;

and means securing said layers in substantially fixed relationship; and

a rupturable container retaining an aqueous alkaline processing solutionpossessing said first pH and an opacifying agent and adapted to effectunidirectional discharge of said containers processing solution betweensaid dyeable polymeric layer and said blue-sensitive silver halideemulsion layer upon application of compressive force to said container;the improvement which comprises an alkaline solution permeable polymericlayer containing light reflecting agent precursor which comprises, uponcontact with said processing solution, first ionic species adapted tointeract with second ionic species to provide a substantially white,inorganic visible light reflecting agent intermediate said dyeablepolymeric layer and said blue-sensitive silver halide emulsion layer,said container fixedly positioned extending transverse a leading edge ofsaid photosensitive element to effect said unidirectional discharge ofsaid processing composition upon application of said compressive forceto said container intermediate said.

polymeric reflecting agent precursor containing layer and saidblue-sensitive silver halide emulsion layer, said reflecting agentprecursor present in a quantity sufficient upon conversion to saidsubstantially white, inorganic visible light reflecting agent to maskdistributed opacifying agent, and said distributed opacifying agenttaken together with said reflecting agent present in a quantitysufficient to prevent exposure of said red-, green-, and blue-sensitivesilver halide emulsion layers in the presence of actinic radiationincident on said dimensionally stable transparent layer and to mask saidcyan, magenta and yellow dyes associated with said red-, greenandblue-sensitive silver halide emulsion layers.

19. A photographic film unit as defined in claim 18 wherein said firstpH is above 9 and said second pH is below 9.

20. A photographic film unit as defined in claim 18 wherein saidopacifying agent is carbon black.

21. A photographic film unit as defined in claim 18 wherein saidreflecting agent precursor is barium ions and said processing solutionincludes sulfate ions.

22. In a process for forming transfer images in color which comprises,in combination, the steps of;

a. exposing a photographic film unit which includes, in combination, acomposite photosensitive structure comprising a first dimensionallystable, liquid impermeable layer opaque to incident actinic radiation, aphotosensitive silver halide layer having associated therewith a dyeimage-forming material which is soluble and diffusible in processingcomposition as a function of exposure of the silver halide layer toincident actinic radiation; a polymeric layer dyeable by said dyeimage-providing material; a second dimensionally stable, liquidimpermeable layer transparent to incident actinic radiation; and meanssecuring said layers in substantially fixed relationship; and means fordistributing a processing composition between said dyeable polymericlayer and the photosensitive silver halide layer next adjacent theretoupon application of compressive force to said container;

b. distributing said processing composition intermediate said dyeablepolymeric layer and the photosensitive silver halide layer next adjacentthereto;

c. effecting thereby development of said silver halide layer;

d. forming thereby an imagewise distribution of mobile dye imageproviding material as a function of the point-topoint degree of silverhalide layer exposure;

e. transferring, by diffusion, at least a portion of said imagewisedistribution of said mobile dye image-providing material to saidpolymeric layer dyeable by said dye image-forming material to provide adye image thereto in terms of said distribution; and

f. maintaining said composite structure intact subsequent to saidprocessing;

the improvement which comprises a layer permeable to processingcomposition solubilized dye image-forming material which comprises lightreflecting agent precursor which includes, upon contact with aprocessing composition, first ionic species adapted to interact withsecond ionic species to provide a substantially white, inorganic visiblelight-reflecting agent intermediate said dyeable polymeric layer andsaid photosensitive silver halide layer, and efiecting therebyinteraction between said first and said secondionic species upon contactof said layer including said light-reflecting agent precursor and saiddistributed processing composition to provide said substantially white,inorganic visible light-reflecting agent intermediate said dyeablepolymeric layer and said photosensitive silver halide layer.

23. A process as defined in claim 22 wherein said means for distributingsaid processing composition comprises container means fixedly positionedextending transverse a leading edge of said composite photosensitivestructure to effect unidirectional discharge of said containersprocessing composition between said layer containing said reflectingagent precursor and the photosensitive silver halide layer next adjacentthereto and said processing composition contains an opacifying agent ina quantity sufi'rcient upon distribution between said layer containingsaid reflecting agent and the photosensitive silver halide layer nextadjacent thereto to prevent exposure of said silver halide layer in thepresence of actinic radiation incident on said dimensionally stabletransparent layer.

24. A process as defined in claim 23 wherein said reflecting agentprecursor is present in a quantity sufficient upon conversion toreflecting agent to mask said distributed opacifying agent.

25. A process as defined in claim 24 wherein said dye image-providingmaterial is a dye which is a silver halide developing agent.

26. A process as defined in claim 25 wherein said dye is substantiallysoluble and diffusible only in the reduced form at a first pH and issubstantially nondiffusible in said reduced form at a second pH.

27. A process as defined in claim 24 wherein said opacifying agent iscarbon black.

28. A process as defined in claim 27 wherein said carbon black ispresent in said processing composition in a concentration within therange of about 3 to 20 grams of carbon black per cc. ofprocessingcomposition.

29. A process as defined in claim 25 wherein said reflecting agentprecursor is disposed in a processing composition permeable polymericmatrix.

30. A process as defined in claim 29 wherein said polymeric matrix isgelatin.

31. A process as defined in claim 29 wherein said reflecting agentprecursor is barium ions and said processing composition containssulfate ions adapted to coact with said barium ions to providesubstantially white, inorganic visible light reflecting barium sulfatepigment.

32. A process as defined in claim 31 wherein said barium and saidsulfate ions are present in stoichiometric quantities sufficient toprovide a reflecting pigment coverage within the range of about 200 to1,000 mgs./ft. reflecting agent.

33. A process as defined in claim 22 including the step of separatingsaid container from said composite structure subsequent to substantialtransfer image formation.

34. In a process as defined in claim 25 which comprises, in combination,the steps of:

a. exposing a photographicfilm unit which is adapted to be processed bypassage through a pair of juxtaposed pressure-applying members and whichincludes, in combination, a composite structure comprising a firstdimensionally stable layer opaque to incident actinic radiation; atleast two selectively sensitized silver halide emulsion layers, each ofsaid silver halide emulsions having associated therewith a dye, which isa silver halide developing agent, of predetermined color, and is solubleand diffusible, in alkaline processing composition as a function of thepoint-to-point degree of exposure of the respective silver halideemulsion associated therewith; a polymeric layer dyeable by said dye; asecond dimensionally stable layer transparent to incident actinicradiation; and means securing said layers in substantially fixedrelationship;

a rupturable container retaining an alkaline-processing compositionpossessing an opacifying agent fixedly positioned and extendingtransverse a leading edge of said photosensitive element to effectdischarge of said containers processing solution between said dyeablepolymeric layer and the photosensitive silver halide emulsion layer nextadjacent thereto upon application of compressive force to saidcontainer; I

applying compressive force to said rupturable container to effectdischarge of said containers alkaline processing composition betweensaid dyeable polymeric layer and the photosensitive silver halideemulsion layer next adjacent thereto;

. efi'ecting development of each of said emulsion layers as a result ofdevelopment;

. immobilizing the dye'associated with each of said emulsion layers as aresult of development;

e. forming thereby an imagewise distribution of mobile dye as a functionof the point-to-point degree of emulsion exposure;

f. transferring, by imbibition, at least a portion of each of saidimagewise distributions of mobile dyes to said polymeric layer dyeableby said dyes to provide thereto a dye image; and

g. maintaining said composite structure intact subsequent to saidprocessing;

the improvement which comprises a layer permeable to processingcomposition diffusible dye containing lightreflecting agent precursorwhich comprises,-upon contact with said alkaline processing composition,first ionic species adapted to interact with second ionic species toprovide a substantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and the photosensitivesilverhalide emulsion layer next adjacent thereto, said containerfixedly positionedextending transverse a leading edge of saidphotosensitive element to effect unidirectional discharge of saidprocessing composition upon said application of compressive force tosaid container intermediate said reflecting agent predominant spectralsensitivity to a separate region of the spectrum and the dye associatedwith each of said emulsion layers possesses a spectral absorption rangesubsequent to processing substantially complementary to the predominantsensitivity range of its associated emulsion.

36. A process as defined in claim 35 wherein said composite structureincludes at least one polymeric acid layer positioned intermediate atleast one of said dimensionally stable opaque layer and the nextadjacent photosensitive silver halide layer,

and said dimensionally stable transparent layer and the next adjacentdyeable polymeric layer and said polymeric acid layers containingsufficient acidifying groups to effect reduction of an alkalineprocessing solution possessing a first pH at which said dyes aresubstantially soluble and diffusible to a second pH at which said dyesare substantially nondiffusible and including the step of transferring,by diffusion, subsequent to substantial transfer image formation, asufficient portion of the ions of said alkaline processing solution tosaid polymeric acid layers to thereby reduce the alkalinity of saidsolution from said first pH to said second pH. i A

37. In a process of forming transfer, images in color as defined inclaim 38 which comprises, in. combination, the steps of:

a. exposing a photographic film unit which is adapted to be processed bypassing said unit between a pair of juxtaposed pressure-applying membersand which includes, in combination, a photosensitive element comprisinga laminate. containing, as essential layers, in sequence, adimensionally stable alkaline. solution impermeable opaque layer; ared-sensitive silver halide emulsion layer having associated therewithcyan dye; a green-sensitive silver halide emulsion layer havingassociated therewith a magenta dye; ablue-sensitive silver halideemulsion layer having associated therewith yellowdye; each of said cyan,magenta and yellow dyes beingsilver halide developing agents and solubleand diffusible in aqueous alkaline solution at a first pH; an alkalinesolution permeable polymeric layer dyeable by said dyes; an alkalinesolution permeable transparent polymeric acid layer containingsufficient acidifying groups to effect reduction of an alkalineprocessing solution having said first pH to a;second pH at which saiddyes are substantially insoluble and nondiffusible; a dimensionallystable, alkaline solution impermeable transparent layer; z y I arupturable 7 container retaining an aqueous alkalineprocessing solutionpossessing said first pH and an opacifying agent in a quantitysufficient toprevent exposure of said red-, greenand blue-sensitivesilver halide emulsions in the presence of actinic radiation incident onsaid dimensionally stable transparent layer fixedly positioned andextending transverse a leading edge of said photosensitive element toeffect unidirectional discharge of said container's processing solutionintermediate said dyeable polymeric layer and said blue-sensitive silverhalide emulsion layer upon application of compressive force to saidcontainer; and I said exposure effected by actinic radiation incident onsaid dimensionally stable transparent layer;

b. applying compressive force to. said rupturable container to effectunidirectionaldischarge of said container's alkaline solution betweensaid'dyeable polymeric layer and said blue-sensitive silverhalideemulsion layer;

c. effecting development of the latent image contained in each of saidred-, greenand blue-sensitive silver halide emulsions;

d. immobilizing said yellow, magenta and cyan dye as a result ofdevelopment of their respective associated silver halide emulsions;

e. forming thereby an imagewise distribution of immobile yellow, magentaand cyan dyes as a function of the pointto-point degree of exposure oftheir respective associated silver halide emulsions;

f. transferring, by diffusion, at least a portion of each of saidimagewise distributions of mobile dye to said alkaline solutionpermeable polymeric layer dyeable by said dyes to provide thereto amulticolor dye image;

g. transferring, by diffusion, subsequent to substantial transfer imageformation, a sufficient portion of the ions of said aqueous alkalinesolution to said alkaline solution permeable polymeric acid layer tothereby reduce the alkalinity of said solution from said first pH atwhich said dyes are soluble and diffusible to said second pH at whichsaid dyes are substantially nondiffusible; and

h. maintaining said laminate intact subsequent to said processing;

the improvement which comprises an alkaline solution permeable layerincluding a light-reflecting agent precursor which comprises, uponcontact with said aqueous alkaline processing solution, first ionicspecies adapted to interact with second ionic species to provide asubstantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and said blue-sensitive silverhalide emulsion layer, said rupturable container fixedly positionedextending transverse a leading edge of said photosensitive element toeffect unidirectional discharge of said processing solution containingsaid opacifying agent intermediate said blue-sensitive silver halideemulsion layer and said light-reflecting agent precursor containinglayer, and effecting thereby interaction between said first and saidsecond ionic species upon contact between said light-reflecting agentprecursor layer and said ;istributed processing solution to provide saidsubstantially white, inorganic visible lightreflecting agentintermediate said dyeable polymeric layer and distributed processingcomposition opacifying agent in a quantity efiective to mask saiddistributed opacifying agent.

38. A process as defined in claim 37 wherein said first pH is above 9and said second pH is below 9.

39. A process as defined in claim 37 including the step of separatingsaid container from said laminate subsequent to substantial imageformation.

40. A process as defined in claim 37 wherein said opacifying agent iscarbon black.

41. A process as defined in claim 37 wherein said reflecting agentprecursor is barium ions and said processing solution contains sulfateions.

42. A process as defined in claim 22 wherein said reflecting agentprecursor is present in a quantity sufficient to provide upon contactwith said processing composition reflecting agent effective to mask saiddye image-forming material associated with said photosensitive silverhalide emulsion layer subsequent to processing.

Patent No. 3,647,435 Dated March 7, 1972 Edwin H. Land Inventor( s) It:is certified that: error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 4, line 34, delete "will" Column 7, line 24, ";issovered" shouldbe "discovered-;

line 31, ":imensionally" should be dimensionally.

Column 12, line'7 2, ")nl'" should be )-1- Column 14, line 58, "state"should be "stated- Column 20, line 16-, 'refl eming" should be-reflecting--.

Column 24, line 34, claim 37, "in claim 38 should be changed to read inclaim 36-. I

Column 26, line 9, istributed" should be distributed.

Signed and sealed this 20th day of November 1.973.

(SEAL) Attest:

EDWARD I LFLETCHERJR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents FORM PO-1050 (IO-69) uscoMM-Dc scans9 9 0.5,GOVERNMEN PRINTING OFFICE I959 0-366-33l

2. A photographic film unit as defined in claim 1 wherein saidreflecting precursor is present in a quantity sufficient to provide,upon contact with said processing composition, said substantially white,inorganic visible light reflecting agent effective to mask said dyeimage-forming material associated with said photosensitive silver halidelayer subsequent to processing.
 3. A photographic film unit as definedin claim 1 wherein said means for distributing a processing compositioncomprises container means fixedly positioned extending transverse aleading edge of said photosensitive element to effect unidirectionaldischarge of said container''s processing composition between said layercontaining said reflecting agent precursor and the photosensitive silverhalide layer next adjacent thereto and said processing compositioncontains an opacifying agent in a quantity sufficient upon distributionbetween said layer containing said reflecting agent precursor and thephotosensitive silver halide layer next adjacent thereto to preventexposure of said silver halide layer in the presence of actinicradiation incident on said dimensionally stable transparent layer.
 4. Aphotographic film unit as defined in claim 3 wherein said reflectingagent precursor is present in a quantity sufficient upon conversion toreflecting agent to mask said distributed opacifying agent subsequent toprocessing.
 5. A photographic film unit as defined in claim 4, whereinsaid dye image-providing material is a dye which is a silver halidedeveloping agent.
 6. A photographic film unIt as defined in claim 5wherein said opacifying agent is carbon black.
 7. A photographic filmunit as defined in claim 6 wherein said carbon black is present in saidprocessing composition in a concentration within the range of about 3 to20 grams of carbon black per 100 cc. of processing composition.
 8. Aphotographic film unit as defined in claim 5 wherein said aqueousalkaline solution contains a film-forming polymeric material.
 9. Aphotographic film unit as defined in claim 8 wherein said reflectingagent precursor is barium ions and said processing composition containssulfate ions adapted to react with said barium ions to providesubstantially white, inorganic, visible light reflecting barium sulfatepigment.
 10. A photographic film unit as defined in claim 9 wherein saidbarium ions and said sulfate ions are present in substantiallystoichiometric quantities sufficient to provide a barium sulfatecoverage of from about 200 to 1,000 mgs./ft.2 reflecting agent.
 11. Aphotographic film unit as defined in claim 5 wherein said reflectingagent precursor is disposed in a polymeric matrix permeable toprocessing composition solubilized dye.
 12. A photographic film unit asdefined in claim 11 wherein said polymeric matrix is gelatin.
 13. Aphotographic film unit as defined in claim 5 wherein said photosensitiveelement comprises at least two selectively sensitized silver halideemulsion layers each having a dye which dye is a silver halidedeveloping agent of predetermined color associated therewith, each ofsaid dyes soluble and diffusible in alkaline processing composition as afunction of the point-to-point degree of exposure of the respectiveemulsion associated therewith.
 14. A photographic film unit as definedin claim 13 wherein each of said selectively sensitized photosensitivesilver halide emulsions has predominant spectral sensitivity to separateregions of the spectrum and the dye associated with each of said silverhalide emulsion layers possesses a spectral absorption range subsequentto processing substantially complementary to the predominant sensitivityrange of its associate emulsion layer.
 15. A photographic film unit asdefined in claim 14 wherein each of said silver halide emulsion layersand its associated dye is separated from the next adjacent silver halideemulsion layer and its associated dye by an alkaline solution permeablepolymeric interlayer.
 16. A photographic film unit as defined in claim 4wherein said processing composition is an aqueous alkaline processingcomposition and said film unit additionally contains at least one acidiclayer positioned intermediate at least one of said dimensionally stableopaque layer and the photosensitive silver halide emulsion layer nextadjacent thereto, and said dimensionally stable transparent layer andthe dyeable polymeric layer next adjacent thereto.
 17. A photographicfilm unit as defined in claim 16 wherein said acidic layer comprises apolymeric acid layer containing sufficient acidifying groups to effectreduction of said processing solution from a first pH at which said dyeis substantially soluble and diffusible to a second pH at which said dyeis substantially nondiffusible.
 18. In a photographic film unit asdefined in claim 17 which is adapted to be processed by passing saidunit between a pair of juxtaposed pressure-applying members and whichcomprises, in combination, a composite structure containing, asessential layers, in sequence, a dimensionally stable, liquidimpermeable opaque layer; an alkaline solution permeable polymeric layercontaining cyan dye; a red-sensitive silver halide emulsion layer; analkaline solution permeable polymeric layer containing magenta dye; agreen-sensitive silver halide emulsion layer; an alkaline solutionpermeable polymeric layer containing yellow dye; a blue-sensitive silverhalide emulsion layer, each of said cyan, magenta and yellow dyes beingsilver halide developing agents and being soluble and diffusible in anaqueous alkaline solution at a first pH; an alkaline solution permeabletransparent polymeric layer dyeable by said dyes; an alkaline solutionpermeable transparent polymeric acid layer containing sufficientacidifying groups to effect reduction of a processing solution havingsaid first pH to a second pH at which said dyes are substantiallynondiffusible; a dimensionally stable, liquid impermeable transparentlayer; and means securing said layers in substantially fixedrelationship; and a rupturable container retaining an aqueous alkalineprocessing solution possessing said first pH and an opacifying agent andadapted to effect unidirectional discharge of said container''sprocessing solution between said dyeable polymeric layer and saidblue-sensitive silver halide emulsion layer upon application ofcompressive force to said container; the improvement which comprises analkaline solution permeable polymeric layer containing light reflectingagent precursor which comprises, upon contact with said processingsolution, first ionic species adapted to interact with second ionicspecies to provide a substantially white, inorganic visible lightreflecting agent intermediate said dyeable polymeric layer and saidblue-sensitive silver halide emulsion layer, said container fixedlypositioned extending transverse a leading edge of said photosensitiveelement to effect said unidirectional discharge of said processingcomposition upon application of said compressive force to said containerintermediate said polymeric reflecting agent precursor containing layerand said blue-sensitive silver halide emulsion layer, said reflectingagent precursor present in a quantity sufficient upon conversion to saidsubstantially white, inorganic visible light reflecting agent to maskdistributed opacifying agent, and said distributed opacifying agenttaken together with said reflecting agent present in a quantitysufficient to prevent exposure of said red-, green-, and blue-sensitivesilver halide emulsion layers in the presence of actinic radiationincident on said dimensionally stable transparent layer and to mask saidcyan, magenta and yellow dyes associated with said red-, green- andblue-sensitive silver halide emulsion layers.
 19. A photographic filmunit as defined in claim 18 wherein said first pH is above 9 and saidsecond pH is below
 9. 20. A photographic film unit as defined in claim18 wherein said opacifying agent is carbon black.
 21. A photographicfilm unit as defined in claim 18 wherein said reflecting agent precursoris barium ions and said processing solution includes sulfate ions. 22.In a process for forming transfer images in color which comprises, incombination, the steps of: a. exposing a photographic film unit whichincludes, in combination, a composite photosensitive structurecomprising a first dimensionally stable, liquid impermeable layer opaqueto incident actinic radiation, a photosensitive silver halide layerhaving associated therewith a dye image-forming material which issoluble and diffusible in processing composition as a function ofexposure of the silver halide layer to incident actinic radiation; apolymeric layer dyeable by said dye image-providing material; a seconddimensionally stable, liquid impermeable layer transparent to incidentactinic radiation; and means securing said layers in substantially fixedrelationship; and means for distributing a processing compositionbetween said dyeable polymeric layer and the photosensitive silverhalide layer next adjacent thereto upon application of compressive forceto said container; b. distributing said processing compositionintermediate said dyeable polymeric layer and the photosensitive silverhalide layer next adjacent thereto; c. effecting thereby development ofsaid silver halide layer; d. forming thereby an imagewise distributionof mobile dye image-providing material as a function of thepoint-To-point degree of silver halide layer exposure; e. transferring,by diffusion, at least a portion of said imagewise distribution of saidmobile dye image-providing material to said polymeric layer dyeable bysaid dye image-forming material to provide a dye image thereto in termsof said distribution; and f. maintaining said composite structure intactsubsequent to said processing; the improvement which comprises a layerpermeable to processing composition solubilized dye image-formingmaterial which comprises light reflecting agent precursor whichincludes, upon contact with a processing composition, first ionicspecies adapted to interact with second ionic species to provide asubstantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and said photosensitive silverhalide layer, and effecting thereby interaction between said first andsaid second ionic species upon contact of said layer including saidlight-reflecting agent precursor and said distributed processingcomposition to provide said substantially white, inorganic visiblelight-reflecting agent intermediate said dyeable polymeric layer andsaid photosensitive silver halide layer.
 23. A process as defined inclaim 22 wherein said means for distributing said processing compositioncomprises container means fixedly positioned extending transverse aleading edge of said composite photosensitive structure to effectunidirectional discharge of said container''s processing compositionbetween said layer containing said reflecting agent precursor and thephotosensitive silver halide layer next adjacent thereto and saidprocessing composition contains an opacifying agent in a quantitysufficient upon distribution between said layer containing saidreflecting agent and the photosensitive silver halide layer nextadjacent thereto to prevent exposure of said silver halide layer in thepresence of actinic radiation incident on said dimensionally stabletransparent layer.
 24. A process as defined in claim 23 wherein saidreflecting agent precursor is present in a quantity sufficient uponconversion to reflecting agent to mask said distributed opacifyingagent.
 25. A process as defined in claim 24 wherein said dyeimage-providing material is a dye which is a silver halide developingagent.
 26. A process as defined in claim 25 wherein said dye issubstantially soluble and diffusible only in the reduced form at a firstpH and is substantially nondiffusible in said reduced form at a secondpH.
 27. A process as defined in claim 24 wherein said opacifying agentis carbon black.
 28. A process as defined in claim 27 wherein saidcarbon black is present in said processing composition in aconcentration within the range of about 3 to 20 grams of carbon blackper 100 cc. of processing composition.
 29. A process as defined in claim25 wherein said reflecting agent precursor is disposed in a processingcomposition permeable polymeric matrix.
 30. A process as defined inclaim 29 wherein said polymeric matrix is gelatin.
 31. A process asdefined in claim 29 wherein said reflecting agent precursor is bariumions and said processing composition contains sulfate ions adapted tocoact with said barium ions to provide substantially white, inorganicvisible light reflecting barium sulfate pigment.
 32. A process asdefined in claim 31 wherein said barium and said sulfate ions arepresent in stoichiometric quantities sufficient to provide a reflectingpigment coverage within the range of about 200 to 1,000 mgs./ft.2reflecting agent.
 33. A process as defined in claim 22 including thestep of separating said container from said composite structuresubsequent to substantial transfer image formation.
 34. In a process asdefined in claim 25 which comprises, in combination, the steps of: a.exposing a photographic film unit which is adapted to be processed bypassage through a pair of juxtaposed pressure-applying memBers and whichincludes, in combination, a composite structure comprising a firstdimensionally stable layer opaque to incident actinic radiation; atleast two selectively sensitized silver halide emulsion layers, each ofsaid silver halide emulsions having associated therewith a dye, which isa silver halide developing agent, of predetermined color, and is solubleand diffusible, in alkaline processing composition as a function of thepoint-to-point degree of exposure of the respective silver halideemulsion associated therewith; a polymeric layer dyeable by said dye; asecond dimensionally stable layer transparent to incident actinicradiation; and means securing said layers in substantially fixedrelationship; a rupturable container retaining an alkaline-processingcomposition possessing an opacifying agent fixedly positioned andextending transverse a leading edge of said photosensitive element toeffect discharge of said container''s processing solution between saiddyeable polymeric layer and the photosensitive silver halide emulsionlayer next adjacent thereto upon application of compressive force tosaid container; b. applying compressive force to said rupturablecontainer to effect discharge of said container''s alkaline processingcomposition between said dyeable polymeric layer and the photosensitivesilver halide emulsion layer next adjacent thereto; c. effectingdevelopment of each of said emulsion layers as a result of development;d. immobilizing the dye associated with each of said emulsion layers asa result of development; e. forming thereby an imagewise distribution ofmobile dye as a function of the point-to-point degree of emulsionexposure; f. transferring, by imbibition, at least a portion of each ofsaid imagewise distributions of mobile dyes to said polymeric layerdyeable by said dyes to provide thereto a dye image; and g. maintainingsaid composite structure intact subsequent to said processing; theimprovement which comprises a layer permeable to processing compositiondiffusible dye containing light-reflecting agent precursor whichcomprises, upon contact with said alkaline processing composition, firstionic species adapted to interact with second ionic species to provide asubstantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and the photosensitive silverhalide emulsion layer next adjacent thereto, said container fixedlypositioned extending transverse a leading edge of said photosensitiveelement to effect unidirectional discharge of said processingcomposition upon said application of compressive force to said containerintermediate said reflecting agent precursor containing layer and saidsilver halide emulsion layer next adjacent thereto, and effectingthereby interaction between said first and said second ionic speciesupon contact of said light reflecting agent precursor layer with saiddistributed processing composition to provide said substantially white,inorganic visible light-reflecting agent intermediate said dyeablepolymeric layer and distributed processing composition opacifying agentin a quantity effective to mask said distributed opacifying agent.
 35. Aprocess as defined in claim 34 wherein each of said selectivelysensitized silver halide emulsion layers possess predominant spectralsensitivity to a separate region of the spectrum and the dye associatedwith each of said emulsion layers possesses a spectral absorption rangesubsequent to processing substantially complementary to the predominantsensitivity range of its associated emulsion.
 36. A process as definedin claim 35 wherein said composite structure includes at least onepolymeric acid layer positioned intermediate at least one of saiddimensionally stable opaque layer and the next adjacent photosensitivesilver halide layer, and said dimensionally stable transparent layer andthe next adjacent dyeable polymeric layer and said polymeric acid layerscontaining suFficient acidifying groups to effect reduction of analkaline processing solution possessing a first pH at which said dyesare substantially soluble and diffusible to a second pH at which saiddyes are substantially nondiffusible and including the step oftransferring, by diffusion, subsequent to substantial transfer imageformation, a sufficient portion of the ions of said alkaline processingsolution to said polymeric acid layers to thereby reduce the alkalinityof said solution from said first pH to said second pH.
 37. In a processof forming transfer images in color as defined in claim 38 whichcomprises, in combination, the steps of: a. exposing a photographic filmunit which is adapted to be processed by passing said unit between apair of juxtaposed pressure-applying members and which includes, incombination, a photosensitive element comprising a laminate containing,as essential layers, in sequence, a dimensionally stable alkalinesolution impermeable opaque layer; a red-sensitive silver halideemulsion layer having associated therewith cyan dye; a green-sensitivesilver halide emulsion layer having associated therewith a magenta dye;a blue-sensitive silver halide emulsion layer having associatedtherewith yellow dye; each of said cyan, magenta and yellow dyes beingsilver halide developing agents and soluble and diffusible in aqueousalkaline solution at a first pH; an alkaline solution permeablepolymeric layer dyeable by said dyes; an alkaline solution permeabletransparent polymeric acid layer containing sufficient acidifying groupsto effect reduction of an alkaline processing solution having said firstpH to a second pH at which said dyes are substantially insoluble andnondiffusible; a dimensionally stable, alkaline solution impermeabletransparent layer; a rupturable container retaining an aqueousalkaline-processing solution possessing said first pH and an opacifyingagent in a quantity sufficient to prevent exposure of said red-,green-and blue-sensitive silver halide emulsions in the presence ofactinic radiation incident on said dimensionally stable transparentlayer fixedly positioned and extending transverse a leading edge of saidphotosensitive element to effect unidirectional discharge of saidcontainer''s processing solution intermediate said dyeable polymericlayer and said blue-sensitive silver halide emulsion layer uponapplication of compressive force to said container; and said exposureeffected by actinic radiation incident on said dimensionally stabletransparent layer; b. applying compressive force to said rupturablecontainer to effect unidirectional discharge of said container''salkaline solution between said dyeable polymeric layer and saidblue-sensitive silver halide emulsion layer; c. effecting development ofthe latent image contained in each of said red-, green- andblue-sensitive silver halide emulsions; d. immobilizing said yellow,magenta and cyan dye as a result of development of their respectiveassociated silver halide emulsions; e. forming thereby an imagewisedistribution of immobile yellow, magenta and cyan dyes as a function ofthe point-to-point degree of exposure of their respective associatedsilver halide emulsions; f. transferring, by diffusion, at least aportion of each of said imagewise distributions of mobile dye to saidalkaline solution permeable polymeric layer dyeable by said dyes toprovide thereto a multicolor dye image; g. transferring, by diffusion,subsequent to substantial transfer image formation, a sufficient portionof the ions of said aqueous alkaline solution to said alkaline solutionpermeable polymeric acid layer to thereby reduce the alkalinity of saidsolution from said first pH at which said dyes are soluble anddiffusible to said second pH at which said dyes are substantiallynondiffusible; and h. maintaining said laminate intact subsequent tosaid processing; the improvement which comprises an alkaline solutionpeRmeable layer including a light-reflecting agent precursor whichcomprises, upon contact with said aqueous alkaline processing solution,first ionic species adapted to interact with second ionic species toprovide a substantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and said blue-sensitive silverhalide emulsion layer, said rupturable container fixedly positionedextending transverse a leading edge of said photosensitive element toeffect unidirectional discharge of said processing solution containingsaid opacifying agent intermediate said blue-sensitive silver halideemulsion layer and said light-reflecting agent precursor containinglayer, and effecting thereby interaction between said first and saidsecond ionic species upon contact between said light-reflecting agentprecursor layer and said distributed processing solution to provide saidsubstantially white, inorganic visible light-reflecting agentintermediate said dyeable polymeric layer and distributed processingcomposition opacifying agent in a quantity effective to mask saiddistributed opacifying agent.
 38. A process as defined in claim 37wherein said first pH is above 9 and said second pH is below
 9. 39. Aprocess as defined in claim 37 including the step of separating saidcontainer from said laminate subsequent to substantial image formation.40. A process as defined in claim 37 wherein said opacifying agent iscarbon black.
 41. A process as defined in claim 37 wherein saidreflecting agent precursor is barium ions and said processing solutioncontains sulfate ions.
 42. A process as defined in claim 22 wherein saidreflecting agent precursor is present in a quantity sufficient toprovide upon contact with said processing composition reflecting agenteffective to mask said dye image-forming material associated with saidphotosensitive silver halide emulsion layer subsequent to processing.